The present invention relates to a method and an apparatus for momentum exchange of a pressurized fluid in which a jet of highly pressurized water is released and its kinetic energy is used for sucking and delivering a fluid including solids, producing a negative pressure for a suction dehydrator apparatus, and transferring from a lower location to a higher.
It is known that a pressure feeder apparatus such as a tube pump is used for sucking and delivering a slurry, concrete milk, or the like including solids. The negative pressure for the suction dehydrator apparatus is commonly developed by means of a venturi type negative pressure generator apparatus.
Such a tube pump or pressure feeder apparatus for delivering a flow containing solids has a resilient tube arranged so as to be deformable by a roller for reducing its cross sectional area through which a given volume of slurry or concrete milk is transferred under pressure. The negative pressure generator apparatus of any venturi type is designed for blowing a jet of pressurized fluid into a venturi and increasing the speed of the fluid enough to produce a negative pressure in the venturi.
The tube pump type pressure feeder apparatus allows the resilient tube to be pressed down by the roller for reducing the cross sectional area, thus increasing the possibility of clogging the resilient tube with the solids contained in the fluid and lowering the operational reliability of the apparatus. Also, as the fluid is forwarded or delivered intermittently, its maximum volume per unit time will be limited.
The tube pump type pressure feeder apparatus is varies in cross sectional area and this will become critical if air (gas) enters the system. Once a flow of air enters the pressure feeder apparatus, it will be compressed hence which will reduce the feeding efficiency and interrupt the feeding action of the apparatus. For several years this has been recognized as a fundamental drawback of common pumps throughout the worldwide industries.
The venturi type negative pressure generator apparatus produces a reduced or negative pressure due to the Bernoulli effect by blowing a jet of pressurized fluid from a jet nozzle into a venturi or throat passage at a near-sonic speed. Although the negative pressure is successfully produced and utilized, the venturi or throat passage of such a jet pump installation will also produce undesirable effects including turbulence and cavitation.
For maintaining a desired feeding efficiency of the jet pump installation, the cross section of the pressurized fluid to be forwarded through it has to remain compatible with the inner diameter of the venturi or throat passage. It is thus necessary for aligning the cross section of the pressurized fluid with the inner diameter of the venturi or throat passage to determine the proper settings of the diameter of the jet nozzle aperture for producing a jet of the pressurized fluid as well as the pressure of a pressurizing pump according to the requirements of the job to be performed.
However, even when the cross section of the pressurized fluid has been maintained compatible with the inner diameter of the venturi or throat passage, and the settings of the diameter of the jet nozzle aperture for producing a jet of the pressurized fluid and the pressure of the pressurizing pump have been determined, there is still a problem. As the negative pressure is produced in the venturi or throat passage, the negative pressure acts as a back pressure against the venturi or throat passage and varies with changes in the volume of the fluid. This prevents the jet pump form liquid from consistently and efficiently producing the negative pressure.
Further, the alignment of the cross section of the pressurized fluid with the inner diameter of the venturi or throat passage is quite difficult and can be effected only by the use of relevant data, knowledge, and skill which have been accumulated since the first introduction of the liquid jet pump.
In addition, an extra portion of the negative pressure has to be calculated as developed outside of the venturi or throat passage. However, when a conduit through which the pressurized fluid is passed is enlarged radially and gradually towards exit end of the conduit, the cross section of the pressurized fluid becomes greater, and thus the reference point for the calculation and to establish any mathematical formula for a practical use cannot be established. Therefore, conventional pressure feeder apparatuses such as liquid jet pumps are only designed on the basis of relevant data, measurements, and rules which have been gained through experience.
If a slurry which includes solids is pumped upward by the liquid jet pump for dredging, its specific gravity may be great enough to cause cavitation, and some of the solids may come into direct contact with or strike the jet nozzle and venturi or throat. The higher the pressure of a jet fluid, the greater resulting damage.
It is common for minimizing cavitation and damage to the inner walls of the jet pump to limit the pressure (including the negative suction pressure and the feeding pressure) used in the pump to pressures in a relatively low range.
As the liquid jet pump is operated under this limited condition, its operating capability will be unstable with changes in any of the nozzle jet pressure, the nozzle aperature diameter, the throat inner diameter, and the distance between the jet nozzle and the entrance of the throat.
If the pressure of the pressurized fluid is increased, its cross section will be enlarged due to the effects of cavitation, and thus cross section will exceed the inner diameter of the entrance of the throat. As a result, a part of the fluid will run backward in the throat or pressure reduction passage and cause solids contained therein to damage the entrance of the throat. To eliminate this problem, the structural balance between the diameter of the aperture of the jet nozzle and the inner diameter of the entrance of the throat has to be determined with great care. Accordingly, a design of the liquid jet pump is assigned to a specific application, and thus its usage as a unit will be limited to a very small range of industrial operations.
The inventor of the present invention has reviewed the fact that an entry of air in the compression or pressure feeder apparatus which varies the volume of a fluid is critical because the air is compressed which reduces or interrupts the efficiency of feeding the fluid. After intensive study of the movement of a jet of water in a water jet pump in relation to the flow of air introduced intentionally, a variety of air mixed type jet pumps were developed in the 1980s for the purpose of solving the foregoing drawbacks.
Since the air mixed type jet pumps were first invented, over 20 years have passed. The air mixed type jet pumps have been modified and improved in order to satisfy a wide range of applications by trying to eliminate the substantial drawbacks including instability of fluid transfer, friction along the inner wall, and cavitation.
The air mixed type jet pumps which were invented and disclosed by the present inventor taught only about the pump's theoretical construction, arrangement, and application usage. Unfortunately, no mathematical formulas for implementing the previous inventions were developed. The air mixed type jet pumps hence are not widely accepted because they are based, like the conventional liquid jet pumps, on relevant data, measurements, and rules gained through a series of experimental applications.
It may be true that the previously developed air mixed type jet pumps invented by me have novel constructions and the functions and advantages thereof are not clearly verified by appreciable theoretical statements that undertake an intended operation.
Since the entry of air in any conventional jet pump is one of the most important conditions to avoid, the air mixed type of jet pumps may not be accepted and utilized widely in the related industries unless the construction, function, and advantages thereof can be proved by a rational explanation with theoretical statements.
It is an object of the present invention to describe the advantages of an air mixed type jet pump having a novel construction, which is very different from any of the conventional jet pumps, and arranged such that its operational performance can be calculated with theoretical statements in order to meet a variety of applications.